In the sector of hygienic-sanitary products (and also in other sectors of the art, such as, for example, the automatic-packaging sector) there commonly find application unwinding devices for supplying web material, equipped with splicing systems (the so-called “splicers”), which enable joining to a web being supplied from a reel that is running out one end of a web of a new reel. The connection is usually made adhesively (for example, with a bi-adhesive tape), and the operation of splicing is performed by cutting the old web immediately after the join so as to reduce to a minimum the length of the “trailing end” that the old web draws along with it (or “overlap”). The operation is performed without stopping the movement of supply of the web: the stations that use the web consequently see the unwinder as a source that supplies a web of virtually infinite length without any interruption.
A splicing device of the type specified above is described in the document U.S. Pat. No. 4,157,934, which is used as model for the preamble of Claim 1.
Albeit having encountered a considerable success over the years, this solution is not free from drawbacks in use.
The corresponding device is, in fact, built as a structure that is as a whole closed both on account of problems of safety and on account of problems of the manufacturing process. In particular, the aim is to provide a structure that is very rigid, in which the distances between the blades and the counterblade that are to make the cut in the web, as well as the distances between the two pressure pads (50, according to the numbering adopted in FIG. 1 of the document U.S. Pat. No. 4,157,934), are reduced. This is done for various reasons, not the least of which is to reduce the time necessary for completing the splicing operation.
In the step of pre-arrangement of the device for carrying out the splicing operation, the operator is thus forced to work in particularly critical conditions. The unwinding devices—and hence the splicing devices associated thereto—are usually mounted in the top part of the machines so as to cause the web supplied thereby to drop down from above. This arrangement is convenient for reasons of encumbrance and because it prevents the unwinder from interfering with the other parts of the machine.
However, to be able to pre-arrange the device for carrying out a new splicing operation, the operator responsible finds himself having to perform a sequence of extremely inconvenient operations.
Usually, after mounting the “new” reel in the unwinder (an operation that is usually performed from the ground with a small crane or hoist), the operator climbs to the top of a ladder in order to bring himself to the same height as the unwinder and, whilst he is at the top of the ladder, leaning forwards to reach over the structures for covering and protecting the machine, he must:
release from the “new” reel the free end that is to be used for the splicing operation;
apply on this free end (the material being usually quite soft—for example, having the consistency of toilet paper or even less) a bi-adhesive tape for a length of 300-400 mm;
insert edgeways the end of the web thus adhesivized in the top slit of the splicing device, getting it to drop until it is brought down in front of the compliant contrast element that is to press the aforesaid free end against the web of the “old” reel;
ensure (operating in conditions of purely visual control—for example observing the descent of the free adhesivized end of the web through a slit of Plexiglas) the exact lateral alignment of the end of the web with the web being unwound; and
finally, block the aforesaid free end of web in the desired position to be able to perform the splicing operation.
The latter operation is particularly inconvenient and difficult because, to be able to activate the corresponding gripping device, the operator must free one of his hands engaged in the operation of insertion and alignment of the web.
The entire operation is further complicated by the fact that, whilst the device is prepared for performing the splicing operation, the machine in which the unwinding device is included continues to function. This means that the operator encounters, at a short distance from the splicing device, the “working” web, which continues to be supplied—even at a rather fast rate—by the unwinding device. In addition, he must prevent any contact with said working web, seeing that even a short and slight contact could result, on account of the fragility of the material, in an undesired tearing of the web with the consequent need to stop the machine and the corresponding work cycle.